1. Field of the Invention
The present invention relates generally to filtration devices, particularly those suited for filtering out amounts of perchlorethylene (perc) from dry cleaning wastewater. More particularly, the present invention is directed to a portable and multiple stage filtration device for use with any sized commercial dry-cleaning machine, in particular smaller sized machines. Additionally, the portable filtration device of the present invention provides the combined features of recycling (for reuse) quantities of perchlorethylene derived from the input wastewater, as well as the ability to reduce, through succeeding filtration stages, a remaining concentration of perc and associated odors to such a degree that an effluent discharge of the device can be safely disposed in conventional (drain) manner.
2. Description of the Prior Art
The concept of water treatment and filtration is well known in the art. In particular, a number of existing devices are known in the prior art for the specific purpose of filtering (treating) wastewater from commercial and industrial dry cleaning operations and in order to remove treatment chemicals which become mixed into the water. The most notable type of treatment chemical known in the dry cleaning industry is perchlorethylene (perc), a very dense, heavy liquid which is well suited for conventional dry cleaning procedures, however this toxic waste is a VOC (volatile organic compound). As is also well known, hazardous waste removal of such chemicals can pose a very expensive option to the dry cleaner operator, thus tempting the operator to either invest in expensive filtration equipment or, alternately, tempting the operator to flaunt government regulations in the illegal dumping or otherwise disposal of the perc-laden wastewater.
A first example of a purification system for dry cleaning wastewater is set forth in U.S. Pat. No. 6,123,838, issued to Grossman, and which teaches a three stage purification process. In the first stage, highly contaminated separator wastewater is put into a solvent separator tank. Liquid solvent settles out of the separator waste tank and sinks to the bottom of the separation tank where it accumulates below the separated water. In the second stage, air bubbles are introduced through the separated water, stripping out much of the solvent which is dissolved in the separated water and reducing the dissolved solvent concentration, the air stripping process further disclosing that it extends the useful life of the granulated carbon in the associated filter. Finally, in stage 3, the air stripped water is passed through the granulated carbon filter, resulting in the carbon purified water having a dissolved solvent of less than 0.7 parts per million, as per their claim.
U.S. Pat. No. 5,653,873, also issued to Grossman, discloses another variation of a system and method for reducing dry cleaning wastewater and which combines an air atomization apparatus and a temperature controlled water injection apparatus. The air atomization apparatus disposes of separator water by misting into the air and/or ground, whereas the temperature controlled injection apparatus uses dry cleaning separator water to create and boil an azeotropic mixture in the still of the dry cleaning machine itself.
Finally, U.S. Pat. No. 5,637,212, issued to Kim, discloses a further treatment variant including a collecting tank to collect wastewater from both a dry cleaning machine and a dry cleaning vacuum press which vacuums wastewater and solvent from garments and which remains after completion of the dry cleaning operation. The collected wastewater is pumped through filters and an elevated separation tank, wherein the heavier than water perc separates from the water. The partially purified water then flows through a re-circulation conduit above a separation level in the separation tank and which flows, by virtue of gravity, back down for re-circulation through the filters and then pumped up again to the separation tank for additional filtering and separation of the solvents and other contaminants. In this manner, the wastewater can be recirculated as many times as needed to purify the water, after which it is flowed to a heating chamber for vaporizing and discharge to the atmosphere as steam. Additional types of large scale perc removal equipment are known in the art and particular reference is made to U.S. Pat. No. 4,780,218, issued to Kohler, and U.S. Pat. No. 5,236,580, issued to Kelleher.
The present invention is directed a portable and multiple stage filtration device for use with any sized commercial dry-cleaning machine, in particular smaller sized machines. In particular, the perc treatment system of the present invention is a particular improvement over the Grossman ""838 device in that it provides an enhanced five stage perc removal and odor treatment assembly, and into which is incorporated an element filter, which does not ever have to be changed, into a portable sized unit, typically a fluid holding basin no larger than a five (5) gallon bucket. Additionally, the portable filtration device of the present invention again provides the combined features of recycling (for reuse) quantities of perchlorethylene derived from the input wastewater, as well as the ability to reduce, through the succeeding filtration stages, a remaining concentration of perc and associated odors to such a degree that an effluent discharge of the device can be safely disposed in conventional (drain) manner.
An enclosed basin, typically a five gallon bucket is provided, within which is emplaced a first elongated module is arranged within the basin at a first location. The first module is separated into upper and lower sections, the upper incorporating a porous membrane stack and an element fouler for accomplishing initial filtration of the wastewater for foreign debris and for controlled delivery into the lower section which in turn incorporates a hyper filtration separation (for perc) and filtration process for accomplishing substantial recovery of the chemical contaminant (perchlorethylene).
A second elongated module is arranged within the basin at a second spaced apart location relative to the first module, a series of exterior and porous membranes interconnect the first and second modules as well as inwardly opposing wall edges of the basin proximate the modules and in order to divide the basin into first and second zones for stage III. The second module includes an upper section containing a wet activated carbon, and which may use other suitable materials for this expansion medium.
An element filter is utilized within a lower stage of the second module in order to create a condition for trapping perc and forcing it, in a foaming and vaporous stage, into the upwardly situated expansion medium. The element filter includes both downwardly extending and reverse upwardly extending lines. An air diffuser (air stone) is located in the enlarged reverse line, causing it to foam from the water. Continual action forces significant quantities of the foamy contaminant vapor to be forced upwardly, into the expansion medium, concurrent with the second module discharging, into the second zone of the third filtering stage. Also, by inducing ozone in the element filter it greatly increases the effectiveness of the stage. It also produces an acid that keeps these stages free from fungi; further, ozone is not needed in order for the element filter to work.
A third elongated module is arranged within the basin at a further specified location within the second zone of stage III. A line extends from the second module to the third module (vapor tube), the third module includes a top mounted fan for creating a vacuum pressure through the line in order to draw, from the second module, the contaminant vapor which is absorbed by a dry activated carbon within the third module concurrent with venting a residual air discharge.
A fourth (typically smaller) elongate module is located within the basin in proximity to the third module, a communication passage extending between the third and fourth modules. The lower portion of the third module incorporates a zeolitic refinery process for removing additional odorous contaminates (typically not perc) from the substantially processed wastewater admitted through an opening located in a lower portion of the third module. A discharge line extends from the fourth module and iteratively discharging treated water from the device, such as into a catch bucket.